The present invention relates to a speed control device. More particularly, the present invention is directed to a tire safety air-valve which automatically opens to release air from the tire and cause it to become flat when the tires rotation exceeds a given value corresponding to an excess speed. For example, many accidents are caused by driving at excessive speed due to intoxicated drivers, and other drivers acting irresponsibly. Under such driving conditions and when using the tire safety system of the present invention, accidents caused by speed can be avoided because the tires of such vehicles driven at excessive speed will automatically become flat. In many of the safety systems of vehicles known in the art, the mechanisms are very complicated rendering them unacceptable for commercial use or availability. Also, most systems do not self-operate automatically without driver involvement.